Expression of Human Flt3 Ligand in Pichia
pastoris and Its Biological Characteristics
XU Zhi-Xiang, ZHU Jian-Kun, ZHANG Zhi-Hong1, LI
Ying, LU Yan, HUANG Wei-Da1, ZHANG Xue-Guang*
( Biotechnology Research Institute, Suzhou Medical College, Suzhou
215007, China; 1Department
of Biochemistry, Fudan University, Shanghai 200433, China )
Abstract Flt3 ligand(FL) is a cytokine
that stimulates the proliferation and differentiation of hematopoietic stem
cells/progenitors. In order to obtain high level of recombinant human soluble
FL(rhFL) production, an artificial gene for rhFL was synthesized by using
favored genetic codons of the yeast Pichia pastoris. Then the gene was cloned
into the vector pPICzαA and the resulting construct was introduced into Pichia
pastoris for expression. It was found that it was possible to obtain
biologically active rhFL with a yield of over 30 mg/L of yeast culture. The
rhFL stimulated colony formation from cord blood. rhFL, SCF, GM-CSF and IL-3
are the most promising combination for the in vitro expansion of
stem/progenitor cells. It was also showed that rhFL increased the induction of
dendritic cells from cord blood in combination with GM-CSF, TNFα and IL-4. Interestingly,
rhFL stimulated the growth of an endothelial cell line； this effect has not been
reported before.
Key words recombinant human soluble Flt3
ligand(rhFL)； Pichia pastoris； hematopoietic colony
formation； dendritic cells； endothelial cell
Received: November 8,
1999 Accepted: December 27, 1999
This work was supported by a grant from the Ministry of Military Industry of
china, No. Y5573162 and a grant from IAEA Foundation, No. CPR/9/025
* Corresponding author: Tel, 86-512-5196902; Fax, 86-512-5194908; e-mail, [email protected]